Figure 1.
Karyogram with chromosome arranged into a standardized format.
G-banding and karyotype analysis were used to further confirm the changes of chromosomes in number and structure either in untreated control group (line 1) or simulated microgravity group (line 2 and 3). Chromosome breakages are marked with arrows. The karyotypes are the results of further analysis based on G-banding indicated there was neither chromosome gain or loss, nor deletion, inversion and/or translocation of chromosomes.
Table 1.
Number of chromosomes kept under simulated microgravity for 72
Figure 2.
Changes in ATR expression in 8 samples after the cells were kept under simulated microgravity for 72 hours.
Quantitative real-time PCR was used to analyze the expression of ATR, and the expression of ATR becomes more than 1.5 times larger in samples 1,2,3,5 and 7, and a slightly larger in samples 4 and 8, while smaller in sample 6 after the cells were kept under simulated microgravity for 72 hours. The expression of ATR increases in most of human beings. The relative expression rate in mean± S.E. (n = 3).
Figure 3.
Significant decreases in Mitotic index of PBL cells were kept under simulated microgravity for 72 hours.
The data represents mean±S.E. (n = 3). *0.01<P<0.05 and **P<0.01 (-test as compared to control group).
Figure 4.
Number of chromosome fragile sites in 100 cells of 3 independent samples.
The PBL cells were cultured in folate-free M199 and 0.4 µM aphidicolin added medium. 100 mitotic images of were collected from each sample, and both the number of cells observed and the number of chromosomes with fragile sites were counted. The chromosome fragile sites are determined according to nonstaining chromosome, chromatid gaps or chromosome breakpoints. The number of chromosome fragile sites is much higher for the cells after the cells being kept under simulated microgravity for 72 hours than that of the untreated control group for the three independent samples. *0.01<P<0.05 and **P<0.01 (-test as compared to control group).
Figure 5.
Loci of chromosome fragile sites were determined using G-banging technique through karyotype analysis of PBL cells of sample No.2.
a-c. untreated control, d-f. simulated microgravity for 72 hours. Chromosome morphology was analyzed using conventional chromosome analysis technique (a and d), and the break point (arrow) can be clearly observed. Both G-banging technique and karyotype analysis were used to further confirm the loci of chromosome fragile site (b, c, d and e). The chromosome fragile sites on chromosomes 1, 2, 3, 11, 16 and 19 are highlighted by arrows by black arrows, except FRA3B by orange arrows, FRA11F by blue arrows, and FRA16D by yellow arrows.
Figure 6.
Loci of chromosome fragile sites were determined using G-banging technique through karyotype analysis of PBL cells of sample No.4.
a-c. untreated control, d-f. simulated microgravity for 72 hours. Chromosome morphology was analyzed using conventional chromosome analysis technique (a and d), and the break point (arrow) can be clearly observed. Both G-banging technique and karyotype analysis were used to further confirm the loci of chromosome fragile sites (b, c, d and e). The chromosome fragile sites on chromosome 2, 3 7, 10, 16, 17 and X are highlighted by black arrows, except FRA3B by orange arrows, and FRA16D by yellow arrows.
Figure 7.
Number of chromosome fragile sites on chromosomes 1 and 2 of 4 independent samples.
100 mitotic images were collected from each sample, and both the number of cells observed and the number of chromosomes with fragile sites were counted. The number of chromosome fragile sites on chromosomes 1 and 2 is much larger for the cells after the cells were kept under simulated microgravity 72*0.01<P<0.05 and **P<0.01 (-test as compared to control group).
Figure 8.
Expression rates of FRA3B, FRA11F and FRA16D of 4 independent samples.
100 mitotic images were collected from each sample, and both the number of cells observed and the number of chromosomes with fragile sites were counted. The expression rates of FRA3B, FRA11F and FRA16D increase after the cells were kept under simulated microgravity for 72*0.01<P<0.05 and **P<0.01 (-test as compared to control group).
Table 2.
List of pathways with P<0.001 under simulated microgravity.
Table 3.
Differentially expressed genes.
Figure 9.
Possible pathway of DNA replication is inhibited which leads to the enhancement of structural chromosome instability under simulated microgravity.